This invention relates generally to the coupling art, and more specifically to certain new and useful improvements in a coupling mechanism for interconnecting a drive spindle and a capping chuck in apparatus for applying screw-type closure elements on successive containers with a predetermined degree of tightness. An example of such apparatus is shown in U.S. Pat. No. 3,031,822, issued May 1, 1962 in the name of George H. Diamond, entitled Chuck for Capping Machines.
In the closure-applying apparatus of U.S. Pat. No. 3,031,822 the coupling mechanism includes a hub fastened to a drive spindle, a pair of drive pins carried by the hub, a collar containing the hub and a floating ring driven by the pins. The floating ring carries a pair of lugs engaging keyways in a coupling member which drives a chuck sleeve through a torsion spring. When the closure has been applied to the container with the preselected degree of tightness, the torsion force of the spring is overcome and the coupling member is rotated relative to the chuck sleeve to a position causing the chuck jaws to open. Thereafter, the chuck sleeve and coupling member are reset.
During such resetting, the lugs on the floating ring and the pins on the hub are subjected to impact forces by associated parts of the mechanism due to the spring torsion force used in the mechanism. With larger size closures, the spring torsion force required to achieve the desired degree of tightness increases markedly. For example, a 28 mm cap might require only 18, whereas a 120 mm cap might require 95 inch lbs. of torque. The increased torque can substantially increase the impact forces on the pins and lugs during the resetting action to a point where such forces can become destructive of the mechanism.
In addition, a second spring is positioned within a hub groove to maintain the coupling hub and collar in predetermined orientation, the collar being rotatable against the bias of the second spring to release the coupling member from the mechanism. Heretofore, the second spring has been assembled by insertion through a slot in the collar, with a stud in the hub engaging one end of the slot to maintain the assembled relation.